1. Field of the Invention
The present invention relates to methods for isolating cells from afterbirth tissue employing pulsatile perfusion.
2. Brief Description of the State of the Art
The afterbirth tissue, an ephemeral organ and associated tissues that develop naturally as a result of gestation, is a source of cellular matter that can be used in biological research and for therapeutic procedures. Stem cells derived from afterbirth tissue are increasingly considered desirable due to the fact that certain cells are pluripotent and believed to have a high potential for research and therapeutic applications.
Umbilical cord blood (UCB) has been identified as an important source of stem cells. Most of the stem cells recovered from UCB are thought to be useful in making blood and blood products and are called “hematopoietic” stem cells (HSC). Currently, collection of UCB is difficult and does not always provide enough useable stem cells. Researchers can use UCB-derived stem cells for transplantation into people who have lost their red and white blood cells through disease (like leukemia or lymphoma) or radiation (which is a common side-effect of chemotherapy or from nuclear radiation from atomic bombs or nuclear power accidents). Recent studies have demonstrated that using greater numbers of UCB-derived HSC increases the success of these kinds of transplants; however, approaches to growing more transplantable HSC from UCB in cell culture have been widely unsuccessful.
Methods for “perfusion” of organs for transplant have been used for the past 15 to 20 years. Perfusion science seeks to maintain an organ's natural function using mechanical means. Perfusion has been mostly utilized in cardiac-thoracic surgery, vascular surgery, and for preservation of organs for transplantation. See, for example, U.S. Pat. No. 6,811,965.
The aim of this invention is to increase numbers of stem cells and other primary cells recovered from the afterbirth tissue in comparison to collection from UCB or independent perfusion of the exsanguinated placenta. Ideally, this should result in more successful transplants and treatments and more cellular matter for use in biological research. The simplicity, speed of collection and the total number of useable cells collected could clinically widen the applicability of stem cell transplants in adults.
There is also a substantial and growing body of evidence that stem cells derived from afterbirth tissue may have broader potential for becoming non-hematopoietic (not blood related) cells, such as liver cells, heart cells and nerve cells. If proven true, non-HSC recovered from the perfusion of afterbirth tissue could prove to be a powerful tool in stem cell research.
There are at least two methods typically used to obtain stem cells from the umbilical cord or placenta. The first method involves simply draining blood from the placenta and/or umbilical cord into a closed sterile collection bag using gravity. U.S. Pat. No. 7,045,148 describes a method which uses perfusion to extract cells from the placenta after exsanguinations of the umbilical cord and placenta.
At least one researcher has flushed the placenta with perfusate through the arterial-vein circuit to eliminate tissue residual blood; however, there do not appear to have been any reported extractions of cord blood components, in tandem with the placenta, using pulsatile perfusion or perfusion involving digestive enzymes.
An objective of this invention is to provide an improved method for obtaining pluripotent stem cells, as well as viable primary cells that cannot be described as stem cells because they are incapable of self-renewal.